Design of prototype filters for cosine-modulated filter banks using the constrained least-squares method

A design method for M-channel cosine-modulated filter banks that achieves prescribed passband ripple and stopband attenuation in the subbands is proposed. The method is based on the minimization of a one-dimensional objective function and employs the constrained least-squares method of Selesnick, Lang, and Burrus for designing the prototype filter. When compared with other methods, the proposed method reduced the amplitude-response error in the filter bank at the expense of increased aliasing errors.